A058518 Number of forests of B-trees of order 3 with n labeled leaves.

1, 1, 1, 2, 2, 4, 6, 9, 14, 21, 33, 54, 89, 142, 222, 350, 554, 883, 1406, 2225, 3511, 5539, 8768, 13977, 22417, 36143, 58483, 94818, 153716, 248699, 401054, 644485, 1032794, 1652377, 2642421, 4227547, 6769660, 10851491, 17410292, 27951747

Offset: 0

Author

N. J. A. Sloane, Dec 21 2000

Keywords

• nonn

Crossrefs

Cf. A014535.

Programs

Maple

spec := [C, {B=Union(Z, Subst(M, B)), M=Union(Prod(Z,Z),Prod(Z,Z,Z)), C=PowerSet(B)} ]; [seq(combstruct[count](spec, size=n), n=0..40)];